The present invention provides an advance in the design of an assembly which allows a fixator or fastener, including for example, a screw, or peg, to be inserted through a threaded hole in a stabilizer or implant, such as a plate, anchor or cage, at a variable angle in order to best capture a bone or bone segment with the fixator. The angle of the fixator can subsequently be locked to fix the bone or bone segment relative to the plate, or to fix the plate relative to the bone or bone segment. The invention allows for at least about 10°, and more preferably 15°, of angulation relative to a longitudinal axis of the opening that the fixator is inserted through. The assembly provides the advantage of providing the option to the surgeon of using a locking screw having a threaded head which mates with the threads in the hole to fix the screw at a pre-determined angle, or to use the assembly which comprises a threaded bushing in the hole with a threaded screw at a different desired angle relative to the hole.
There are numerous implant applications that can benefit from a variable angle locking mechanism. Specific examples include use in the small bones, i.e. those bones distal to the elbow and knee and the clavicles, although it is understood, that the mechanism can also be of use in other areas of the body, including the long bones, the pelvis and the spine.